BANGKOK, Thailand – Forensic police collected evidence Friday (September 6th) on a highway in Prachuap Khiri Khan after clashes late Thursday between police and rubber farmers trying to block the road, local media reported.

Police were gathering fragments of ping pong bombs, burnt bicycle inner tubes and stones, MCOT Online reported.

Police said 22 people were injured in the clashes, including officers. A dozen leaders of the protest were detained for questioning.

The crowd gathered to demand the government guarantee better rubber prices for farmers in the province, who say they are struggling with the rising cost of living, The Bangkok Post reported.

Witnesses said the protest was largely peaceful until police fired tear gas at the demonstrators.